75 lines
1.9 KiB
Lua
75 lines
1.9 KiB
Lua
Utils = {}
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--- Returns up to `n` random values from the given array. Will return fewer if `n > #fromArr`
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---@generic T
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---@param fromArr T[]
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---@param n number
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---@return T[]
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function Utils.getNDifferentValues(fromArr, n)
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assert(n >= 0, "n must be a non-negative integer")
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if n > #fromArr then
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n = #fromArr
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end
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local found = 0
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local indexes = {}
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while found < n do
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local randomIndex = math.random(#fromArr)
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if not indexes[randomIndex] then
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found = found + 1
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indexes[randomIndex] = true
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end
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end
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local randoms = {}
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for i in pairs(indexes) do
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randoms[#randoms + 1] = fromArr[i]
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end
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return randoms
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end
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--- Track the number of instances of a given element, instead of needing multiple copies.
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---@class CountSet
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---@field private data table<table, number>
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---@field private elementCount number
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CountSet = {}
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function CountSet.new()
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return setmetatable({ data = {}, elementCount = 0 }, { __index = CountSet })
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end
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function CountSet:add(element)
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local existing = self.data[element]
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if existing then
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self.data[element] = existing + 1
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else
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self.data[element] = 1
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end
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self.elementCount = self.elementCount + 1
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end
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function CountSet:balancedRandomPop()
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if self.elementCount == 0 then
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return
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end
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local toPop = math.random(self.elementCount)
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for element, count in pairs(self.data) do
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toPop = toPop - count
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if toPop <= 0 then
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local newCount = count - 1
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if newCount == 0 then
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self.data[element] = nil
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else
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self.data[element] = newCount
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end
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self.elementCount = self.elementCount - 1
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return element
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end
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end
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end
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function CountSet:iterRandom()
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return function()
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return self:balancedRandomPop()
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end
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end
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